Columbite-Group Minerals from New York Pegmatites: Insights from Isotopic and Geochemical Analyses

Columbite-Group Minerals from New York Pegmatites: Insights from Isotopic and Geochemical Analyses

Blog Article

Columbite crystals from niobium-yttrium-fluorine (NYF) pegmatites lacking zircon or containing metamict cyrtolite were analyzed for major and minor elements (Electron Microprobe (EMP)), trace elements (Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS)), and U-Pb geochronology (Laser AblationMulti-Collector-Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICP-MS)).All four pegmatite localities sampled are hosted by the Proterozoic Fordham gneiss and/or Paleozoic Bedford gneiss (Columbite-(Fe); Kinkel and Baylis localities) and the Manhattan Schist of Lower Paleozoic age (Columbite-(Mn); Fort seattle seahawks socks George and Harlem River Drive localities) and yield Neoacadian ages.The weighted average U-Pb ages are 372.2 ± 8.

2 Ma (Baylis Quarry), 371.3 ± 7.3 and 383.4 ± 8.

9 Ma (Kinkel Quarry); 383 ± 15 Ma (185th St.and Harlem River Drive); and 372 ± 10 Ma (Fort George).A partial metamict zircon (“cyrtolite”) from the Kinkel Quarry yielded a weighted average U-Pb age of 376.9 ± 4.

3 Ma.The Neoacadian ages obtained agree with those determined by thermal ionization mass spectrometry (TIMS) for zircon from Lithium-Cesium-Tantalum (LCT) pegmatites from Connecticut and Maine.No pegmatites temporally associated socksmith santa cruz with the Taconic orogeny were found.The size, lack of common Pb, uniform U concentrations across crystal cross-sections, sufficient but moderate uranium concentrations, lack of metamictization, and consistency in U-Pb isotopic ratios for columbite samples BCB-COL, NYSM #25232, and NYSM #525.

8 suggests they show promise as potential standards for oxide mineral LA-MC-ICP-MS geochronological analyses, however, additional characterization using ID-TIMS would be necessary to develop as such.